I used a Planet Vortex Deflector on a recently conquered planet to save it from having the previous owner from attacking it. Why is it, that he can unleash artifacts against this planet while the Planet Vortex Deflector is active? Is this a bug? not very fun if its meant to be used on enemy planets and can be applied to either enemy planet / own planet.

Help me makes sense of this please.

it only last for 24 hours and it stops all arts from being used.

They said it was active, and the original owner was using artifacts, so this does not help at all.

I can't help anymore than he can though, I don't know why that happened.